The book as a whole, so far as can be judged from the experience the author and others have had in using it during the past year as a text at Columbia, should fit well into any general course in social psychology. It has been increasingly realized that the student's understanding of contemporary problems of government and industry is immensely clarified by a knowledge of the human factors which they involve. This volume supplies a brief account of the essential facts of human behavior with especial emphasis on their social consequences. Part I may be independently used, as it has been with success, in a general course in social psychology. Part II, the "Career of Reason," presents material which many instructors find it highly desirable to use in introductory philosophy courses, but for which no elementary texts are available. The usual textbooks deal with the more metaphysical problems to the exclusion of religion, art, morals, and science, humanly the most interesting and significant of philosophical problems. Where, as in many colleges, the introductory philosophy course is preceded by a course in psychology, the arrangement of the volume should prove particularly well suited. The illustrative material has been drawn, possibly to an unusual extent, from literature. The latter seems to give the student in the vivid reality of specific situations facts which the psychologist is condemned, from the necessities of scientific method, to discuss in the abstract. The book follows more or less closely that part of the syllabus for the course in Contemporary Civilization, which is called "The World of Human Nature," which section of the outline was chiefly the joint product of collaboration by Professor John J. Coss and the author. To the former the author wishes to express his large indebtedness. Also to Miss Edith G. Taber, for her careful and valuable editing of the manuscript in preparation for the printer, he desires to convey his deep appreciation. I. E. _Columbia University, June_ 1920. CONTENTS INTRODUCTION HUMAN TRAITS AND CIVILIZATION PART I--SOCIAL PSYCHOLOGY CHAPTER I TYPES OF HUMAN BEHAVIOR The human animal--The number and variety of man's instincts--Learning in animals and men--The prolonged period of infancy--Consciousness of self and reaction to ideas--Human beings alone possess language--Man the only maker and user of tools. CHAPTER II TYPES OF HUMAN BEHAVIOR AND THEIR SOCIAL SIGNIFICANCE--INSTINCT, HABIT, AND EMOTION